Supervise model regularly snorting lines (7)
I believe the answer is:
oversee
'supervise' is the definition.
(I know that supervise can be written as oversee)
'model regularly snorting lines' is the wordplay.
'regularly' means one should take alternating letters (regularly take one letter, leave next etc.).
'snorting' means one lot of letters goes inside another (snort can mean to ingest through the nose).
'lines' becomes 'verse' (lines of poetry).
The alternating letters of 'model' are 'oe'.
'oe' placed around 'verse' is 'OVERSEE'.
(Other definitions for oversee that I've seen before include "Administer" , "Inspect" , "Supervise, keep an eye on" , "Be responsible for" , "Supervise, monitor" .)